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Ask the Experts

Concussion vs. CTE: What's the Difference?

by Susan Randel  

Q: What is chronic traumatic encephalopathy? Is it the same as a concussion?

A: While both are brain injuries, and there may be a relationship between them, chronic traumatic encephalopathy, known as CTE, and concussion are very different conditions. Discussions of both injuries have been increasingly in the news in recent months.

A concussion is an acute brain injury caused by a blow or other impact to the head that causes the brain to get shaken within the skull. Concussions cause a variety of symptoms, including headache, dizziness, confusion, blurred vision, nausea, vomiting, memory loss, poor coordination, moodiness, fatigue, and light and noise sensitivity. A person who experiences a concussion may or may not lose consciousness at the time of the injury. The hard contact that occurs in sports like football, hockey, and soccer is known to cause concussions. Full recovery from a concussion takes time, but people can return to normal with proper treatment, including rest.

CTE, in contrast, is a progressive brain disease that causes degeneration of cognitive function. It usually starts showing up between ages 40 and 50, with initial symptoms commonly including mood changes, thinking or problem-solving issues, and behavioral changes such as aggression or substance abuse. It eventually progresses to dementia. CTE is believed to result from repeated brain trauma from blows that shake the brain, including concussions. These types of blows occur not only in football but in other hard-contact sports such as boxing, hockey, and soccer, among others. There is no known cure for CTE; treatment is focused on managing the symptoms.

CTE used to be called “punch drunk” because it was first noted in retired boxers whose cognitive abilities, speech, and coordination declined as they aged. When the same symptoms started showing up in retired professional football players, researchers became interested and examined the brains of these men after their deaths. They found tangles of damaged proteins, called tau proteins, in the autopsied brains. Similar tangles are found in the brains of people with Alzheimer’s disease.

What’s especially frightening about CTE is that is it being diagnosed in people who never played professional sports. A number of former high school and college athletes with similar mood and behavioral changes have died young; when their brains were autopsied, the level of brain damage was similar to that of the professional athletes with CTE. The condition has also been diagnosed in military veterans who have encountered repeated blasts from explosions and victims of domestic violence—in short, anyone who has had repeated head blows.

Because of CTE’s association with contact sports, there has been an increase in concern about its relationship to concussions. The link to concussions is not direct—so if you have had one or more concussions from sports you are not automatically going to get CTE. Indeed, researchers believe that repeated smaller asymptomatic subconcussive hits may be a bigger risk factor, especially in athletes who have also had at least one concussion.

Of course, not all football players get CTE. Two players may have the same relative exposure to head blows, and only one may get CTE. Researchers think that a number of factors may contribute to the development of the disease, including how young a person is when he or she starts playing football or other hard contact sports, genetics, and lifestyle choices such as drug and alcohol use. There is currently no diagnostic test to tell who is at risk of developing CTE.

You can find more information about CTE (and concussions) on the website of the Concussion Legacy Foundation.

Also see Spotting and Treating Concussions.